The present invention relates to aerodynamic fairings for a sailboat forestay and more particularly, to a novel controllable cambered forestay fairing which permits the optimum leading edge camber of the sail on both port and starboard tacks.
2. Brief Description of the Prior Art
In the past, it has been a conventional practice to slideably mount the leading edge of a sail onto the forestay of a sailboat by means of spaced-apart piston hanks or by means of an aerodynamic fairing which runs along the full length of the forestay and includes a slotted passageway for carrying the boltrope of the sail. However, problems and difficulties have been encountered when employing such devices which stem largely from the fact that a substantial amount of turbulence is experienced immediately behind the forestay at the crucial area of the sail's luff. Such turbulence is particularly experienced on the leeward side of the sail which greatly limits the sailboat's driving power to windward. Because of the relatively large angle of incidence between the sail and the apparent wind, a leading edge stall or luff occurs as the leading edge of the sail approaches the apparent wind.
When considering the conventional aerodynamics of a sailboat sail, it is well known that unless the oncoming wind is tangent to the forward surface of the sail, the air flow on the leeward side of the sail at its luff will cause turbulence and therefore loss of lift. However, the wind direction immediately in front of the sail is not the apparent wind direction The apparent wind actually bends to leeward just before it reaches the sail and therefore merely using an aerodynamic shape or the older piston hanks for attachment of the leading edge of the sail to the forestay will not reduce or eliminate the turbulence immediately behind the luff of the sail on the leeward side. Furthermore, as the sailboat changes tacks, the same amount of turbulence is experienced on the leeward side since there is no attempt to diverge or re-position the sail attachment with respect to the forestay. In other words, no means is provided for controllably moving the sail attachment means whether it is an aerodynamically shaped foil or piston hanks so as to eliminate the leeward turbulence problem.
Therefore, it has been a longstanding need to provide a novel attachment for the leading edge of a sail to a forestay or the like which permits the optimim leading edge camber of the sail on both port and starboard tacks so as to eliminate turbulence immediately behind the leading edge in the luff area of the sail on the leeward side.